A fuel delivery module is a device inside a fuel tank that allows a vehicle to perform under conditions of low fuel remaining in the fuel tank. The module includes a reservoir that is kept continuously full by, for example, a jet assembly, even when the remainder of the tank is nearly empty. A fuel pump of the module creates pressure conditions at a low pressure side of the pump to operate the jet assembly. A high pressure side of the fuel pump delivers fuel from the reservoir to an engine.
In an electronically pressure controlled fuel system such as an Electronic Returnless Fuel System (ERFS), the pump is supplied a voltage that is pulse width modified (PWM) to control the speed of the pump (this in effect lowers the voltage to the pump as the pump integrates the voltage PWM to a level). When the fuel pump operates at low RPM (e.g., due to low voltage in the range of about 3.5V to 6 V), the pressure at the low pressure side of the fuel pump is low, which is not sufficient to operate the jet assembly.
There is a need to ensure that the jet assembly of a fuel delivery module operates when the pressure at the low pressure side of the fuel pump is insufficient to operate the jet assembly.